Purpose: 1. To identify the receptors on malaria parasites for red cell invasion and on infected red cells for adhesion to endothelium and to placenta. 2. To identify the red cell receptors for each parasite ligand. 3. To identify the minimal domain in the variant antigen for binding to placenta. 4. Test a region on the variant antigen for inducing protection against P. falciparum in Aotus monkeys and for overcoming variation. Accomplishments during the year: 1. The BAEBL receptor is blocked by purified glycophorin C. 2. The receptor domain of AMA1 for binding red cells has been identified as well as the protein on the red cell for binding of AMA1. 3. The difference between Dd2 (no invasion of neuraminidase treated red cells) and Dd2/nm (invasion of neuraminidase treated red cells) has been identified. 4. The domain on infected red cells for binding CSA has been identified on multiple DBL domains.